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[git.git] / string-list.h
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1 #ifndef STRING_LIST_H
2 #define STRING_LIST_H
4 /**
5 * The string_list API offers a data structure and functions to handle
6 * sorted and unsorted arrays of strings. A "sorted" list is one whose
7 * entries are sorted by string value in `strcmp()` order.
9 * The caller:
11 * . Allocates and clears a `struct string_list` variable.
13 * . Initializes the members. You might want to set the flag `strdup_strings`
14 * if the strings should be strdup()ed. For example, this is necessary
15 * when you add something like git_path("..."), since that function returns
16 * a static buffer that will change with the next call to git_path().
18 * If you need something advanced, you can manually malloc() the `items`
19 * member (you need this if you add things later) and you should set the
20 * `nr` and `alloc` members in that case, too.
22 * . Adds new items to the list, using `string_list_append`,
23 * `string_list_append_nodup`, `string_list_insert`,
24 * `string_list_split`, and/or `string_list_split_in_place`.
26 * . Can check if a string is in the list using `string_list_has_string` or
27 * `unsorted_string_list_has_string` and get it from the list using
28 * `string_list_lookup` for sorted lists.
30 * . Can sort an unsorted list using `string_list_sort`.
32 * . Can remove duplicate items from a sorted list using
33 * `string_list_remove_duplicates`.
35 * . Can remove individual items of an unsorted list using
36 * `unsorted_string_list_delete_item`.
38 * . Can remove items not matching a criterion from a sorted or unsorted
39 * list using `filter_string_list`, or remove empty strings using
40 * `string_list_remove_empty_items`.
42 * . Finally it should free the list using `string_list_clear`.
44 * Example:
46 * struct string_list list = STRING_LIST_INIT_NODUP;
47 * int i;
49 * string_list_append(&list, "foo");
50 * string_list_append(&list, "bar");
51 * for (i = 0; i < list.nr; i++)
52 * printf("%s\n", list.items[i].string)
54 * NOTE: It is more efficient to build an unsorted list and sort it
55 * afterwards, instead of building a sorted list (`O(n log n)` instead of
56 * `O(n^2)`).
58 * However, if you use the list to check if a certain string was added
59 * already, you should not do that (using unsorted_string_list_has_string()),
60 * because the complexity would be quadratic again (but with a worse factor).
63 /**
64 * Represents an item of the list. The `string` member is a pointer to the
65 * string, and you may use the `util` member for any purpose, if you want.
67 struct string_list_item {
68 char *string;
69 void *util;
72 typedef int (*compare_strings_fn)(const char *, const char *);
74 /**
75 * Represents the list itself.
77 * . The array of items are available via the `items` member.
78 * . The `nr` member contains the number of items stored in the list.
79 * . The `alloc` member is used to avoid reallocating at every insertion.
80 * You should not tamper with it.
81 * . Setting the `strdup_strings` member to 1 will strdup() the strings
82 * before adding them, see above.
83 * . The `compare_strings_fn` member is used to specify a custom compare
84 * function, otherwise `strcmp()` is used as the default function.
86 struct string_list {
87 struct string_list_item *items;
88 unsigned int nr, alloc;
89 unsigned int strdup_strings:1;
90 compare_strings_fn cmp; /* NULL uses strcmp() */
93 #define STRING_LIST_INIT_NODUP { NULL, 0, 0, 0, NULL }
94 #define STRING_LIST_INIT_DUP { NULL, 0, 0, 1, NULL }
96 /* General functions which work with both sorted and unsorted lists. */
98 /**
99 * Initialize the members of the string_list, set `strdup_strings`
100 * member according to the value of the second parameter.
102 void string_list_init(struct string_list *list, int strdup_strings);
104 /** Callback function type for for_each_string_list */
105 typedef int (*string_list_each_func_t)(struct string_list_item *, void *);
108 * Apply `want` to each item in `list`, retaining only the ones for which
109 * the function returns true. If `free_util` is true, call free() on
110 * the util members of any items that have to be deleted. Preserve
111 * the order of the items that are retained.
113 void filter_string_list(struct string_list *list, int free_util,
114 string_list_each_func_t want, void *cb_data);
117 * Dump a string_list to stdout, useful mainly for debugging
118 * purposes. It can take an optional header argument and it writes out
119 * the string-pointer pairs of the string_list, each one in its own
120 * line.
122 void print_string_list(const struct string_list *p, const char *text);
125 * Free a string_list. The `string` pointer of the items will be freed
126 * in case the `strdup_strings` member of the string_list is set. The
127 * second parameter controls if the `util` pointer of the items should
128 * be freed or not.
130 void string_list_clear(struct string_list *list, int free_util);
133 * Callback type for `string_list_clear_func`. The string associated
134 * with the util pointer is passed as the second argument
136 typedef void (*string_list_clear_func_t)(void *p, const char *str);
138 /** Call a custom clear function on each util pointer */
139 void string_list_clear_func(struct string_list *list, string_list_clear_func_t clearfunc);
142 * Apply `func` to each item. If `func` returns nonzero, the
143 * iteration aborts and the return value is propagated.
145 int for_each_string_list(struct string_list *list,
146 string_list_each_func_t func, void *cb_data);
148 /** Iterate over each item, as a macro. */
149 #define for_each_string_list_item(item,list) \
150 for (item = (list)->items; \
151 item && item < (list)->items + (list)->nr; \
152 ++item)
155 * Remove any empty strings from the list. If free_util is true, call
156 * free() on the util members of any items that have to be deleted.
157 * Preserve the order of the items that are retained.
159 void string_list_remove_empty_items(struct string_list *list, int free_util);
161 /* Use these functions only on sorted lists: */
163 /** Determine if the string_list has a given string or not. */
164 int string_list_has_string(const struct string_list *list, const char *string);
165 int string_list_find_insert_index(const struct string_list *list, const char *string,
166 int negative_existing_index);
169 * Insert a new element to the string_list. The returned pointer can
170 * be handy if you want to write something to the `util` pointer of
171 * the string_list_item containing the just added string. If the given
172 * string already exists the insertion will be skipped and the pointer
173 * to the existing item returned.
175 * Since this function uses xrealloc() (which die()s if it fails) if the
176 * list needs to grow, it is safe not to check the pointer. I.e. you may
177 * write `string_list_insert(...)->util = ...;`.
179 struct string_list_item *string_list_insert(struct string_list *list, const char *string);
182 * Remove the given string from the sorted list. If the string
183 * doesn't exist, the list is not altered.
185 extern void string_list_remove(struct string_list *list, const char *string,
186 int free_util);
189 * Check if the given string is part of a sorted list. If it is part of the list,
190 * return the coresponding string_list_item, NULL otherwise.
192 struct string_list_item *string_list_lookup(struct string_list *list, const char *string);
195 * Remove all but the first of consecutive entries with the same
196 * string value. If free_util is true, call free() on the util
197 * members of any items that have to be deleted.
199 void string_list_remove_duplicates(struct string_list *sorted_list, int free_util);
202 /* Use these functions only on unsorted lists: */
205 * Add string to the end of list. If list->strdup_string is set, then
206 * string is copied; otherwise the new string_list_entry refers to the
207 * input string.
209 struct string_list_item *string_list_append(struct string_list *list, const char *string);
212 * Like string_list_append(), except string is never copied. When
213 * list->strdup_strings is set, this function can be used to hand
214 * ownership of a malloc()ed string to list without making an extra
215 * copy.
217 struct string_list_item *string_list_append_nodup(struct string_list *list, char *string);
220 * Sort the list's entries by string value in `strcmp()` order.
222 void string_list_sort(struct string_list *list);
225 * Like `string_list_has_string()` but for unsorted lists. Linear in
226 * size of the list.
228 int unsorted_string_list_has_string(struct string_list *list, const char *string);
231 * Like `string_list_lookup()` but for unsorted lists. Linear in size
232 * of the list.
234 struct string_list_item *unsorted_string_list_lookup(struct string_list *list,
235 const char *string);
237 * Remove an item from a string_list. The `string` pointer of the
238 * items will be freed in case the `strdup_strings` member of the
239 * string_list is set. The third parameter controls if the `util`
240 * pointer of the items should be freed or not.
242 void unsorted_string_list_delete_item(struct string_list *list, int i, int free_util);
245 * Split string into substrings on character `delim` and append the
246 * substrings to `list`. The input string is not modified.
247 * list->strdup_strings must be set, as new memory needs to be
248 * allocated to hold the substrings. If maxsplit is non-negative,
249 * then split at most maxsplit times. Return the number of substrings
250 * appended to list.
252 * Examples:
253 * string_list_split(l, "foo:bar:baz", ':', -1) -> ["foo", "bar", "baz"]
254 * string_list_split(l, "foo:bar:baz", ':', 0) -> ["foo:bar:baz"]
255 * string_list_split(l, "foo:bar:baz", ':', 1) -> ["foo", "bar:baz"]
256 * string_list_split(l, "foo:bar:", ':', -1) -> ["foo", "bar", ""]
257 * string_list_split(l, "", ':', -1) -> [""]
258 * string_list_split(l, ":", ':', -1) -> ["", ""]
260 int string_list_split(struct string_list *list, const char *string,
261 int delim, int maxsplit);
264 * Like string_list_split(), except that string is split in-place: the
265 * delimiter characters in string are overwritten with NULs, and the
266 * new string_list_items point into string (which therefore must not
267 * be modified or freed while the string_list is in use).
268 * list->strdup_strings must *not* be set.
270 int string_list_split_in_place(struct string_list *list, char *string,
271 int delim, int maxsplit);
272 #endif /* STRING_LIST_H */